Tape feed mechanism



J. A. WEIDENHAMMER ET AL 2,792,217

May 14,1957

' TAPE FEED MECHANISM 15 Sheets-Sheet 1 Filed July 13, 1954 INVENTORS JAMES A.WE|DENHAMMER WALTER s. BLQSLIK ATTO May 14, 1957 J. A. WEIDENHAMMER ETAL TAPE FEED MECHANISM l5 Sheets-Sheet 2 Filed ,July 13, 1954 FIG. 3

226 MRS THC INVENTORS JAMES A. WEIDENHAMMER M y 1957 J. A. WEIDENHAMMER ETAL 2,792,217

' TAPE FEED MECHANISM Filed July 13, 1954. 13 sneaks-sheet 5 FIG. 4' F5 FIG. 5 H

' INVENTORS .JAMES A- WEIDENHAMMER WALTER S. BUSLIK BY/-0 v ATT NEY May 14, 1957 J. A. WEIDENHAMMER ET AL TAPE FEED MECHANISM 1s Sheets-Sheet 4 Filed July 13, .1954

R E M m .H mum Nmmw. EE WW. s m aw w m ATT NEY May 14, 1957 J. A. WE IDENHAMMER ETAL TAPE FEED MECHANISM l3 Sheets-Sheet 5 Filed July 15, 1954 FIG. l0

INVENTORS JAMES A. WEIDENHAMMER wg gl? S. BUSLIK BY ATT NEY J. A. WEIDENHAMMER ETAL 2,792,217

TAPE FEEDYMECHANISM May 14, I957 13 'SheetsSheet 6 Filed July 13, 1954 36 FIG. ll

| e o INVENTORS a JAMES A.WEIDENHAMMER H Y WALTER .BUS LIK VBY ATTOR EY y 1957 J. A. WEIDENHAMMER ETAL- 2,792,217-

TAPE FEED MECHANISM 13 Sheets-Sheet 7 Filed July is, 1954.

FIG. l3

INVENTORS JAMES A. WEIDENHAMMER ATTO NEY y 14, 7 J. A. WElDENHAMME ETAL 2,792,217

TAPE FEED MECHANISM '13 Sheets-Sheet 8 Filed July 137, i954 INVENTORS JAMES A.WEIDENHAMMER WALTER S. BUS LIK ATTOR EY FIG. l4

J. A. WEIDENHAMMER ET AL May 14, 1957 TAPE FEED MECHANISM I 13 Sheets-Sheet 9 Filed July 15, 1954 V INVENTORS JAMES A. WEIDENHAMMER WALTER S. BUSLIK BY KQ W ATTOR EY 1957 J. A. WEIDENHAMMER ET AL 2,792,217

TAPE FEED MECHANISM 13 Sheets-Sheet 10 Filed July 13, 1954 F l G. 2|

FIG. 22

INVENTQRS JAMES AWEIDENHAMMER wfiTER s. BUSLIK ATTOKNQEJY y 1957 J. A. WEIDENHAMMER ETAL 2,792,217

TAPE FEED MECHANISM l3 Sheets-Sheet 12 Filed July 15, 1954.

FIG. 27

PTI

+ IOV PIl FIG.28

INVENTORS JAMES A.WE|DENHAMMER WALTER BY A 6."

BINARY TRIGGER BUSLIK ATTOR EY y 1957 J. A. WEIDENHAMMER ETAL 2,792,217

TAPE FEED MECHANISM Filed July 15, 1954- 13 Sheets-Sheet l RRK RI HD RC 440 u 500 a 115v A.c.

mvzm'ons JAMES WEIDENHAMMER WALTER s. epsuK BY W ATTO NEY United States. Patent TAPE FEED MECHANISM James A. Weidenhammer and Walter S. Buslik, Poughkeepsie, N. Y., assignors to International Business Machines Corporation, New York, N. Y., a corporation of New York Original application May 28, 1952, Serial No. 290,396. Divided and this application July 13, 1954, Serial No. 443,062

Claims. (Cl. 271-2.3)

This invention relates to a machine for reeling, unreeling and feeding tape.

More particularly, the invention herein relates to a machine for feeding a record tape through a record reading and/or reproducing head. The invention was conceived as an adjunct to an electronic computing machine, but may be usefully employed in other environments where high speed tape feeding is a requirement.

With the advent of electronic computing machines, the need for rapid data input and data recording means has become very acute. Heretofore the speed at which data could be read from or recorded upon a record medium was in part limited by the speed at which existing equipment could feed such records through a record sensing or recording station.

The present invention contemplates a record tape feeding mechanism capable of feeding a record tape through a reading and recording head at a speed of 200 feet per second, with an acceleration and deceleration time of not more than .005 second, and with the ability to reverse direction of tape feed in ten milliseconds or less.

Production of high speed tape feeding equipment having rapid acceleration, rapid deceleration, and rapid braking rates encounters the clifficulty that record tapes have no great tensile strength and that machines designed to handle such tapes must, therefore, impose no substantial torque on the tape. It is, therefore, the primary object of this invention to provide a record tape feeding mechanism which is capable of feeding a record tape through a record reading or reproducing head at high speed without imposing any substantial torque on such tape.

It is a further object of the invention to provide a record tape feeding mechanism having a high rate of tape acceleration and deceleration.

it is a further object of the invention to provide a record tape feeding mechanism having tape braking means which is capable of instantaneously halting tape feed.

Withal, it is an objective of this invention to provide a record tape feeding mechanism having means for feeding a record tape through a record reading and/ or reproducing head that imposes a minimum amount of torque on the record tape being fed.

These and other objects and advantages of the invention are attained in a tape feeding mechanism having a pair of tape reels which may be independently rotated for either reeling or unreeling tape thereon. It is contemplated that each tape reel be power driven through a clutch mechanism which is adapted to selectively drive the reel in either direction.

The clutch mechanisms herein are under control of the position of a tape loop depending from each reel and the control system is so designed as to maintain the tape loops substantially constant in length.

The tape loops provide a tape source upon which a tape feeding mechanism may call for tape to be fed through a record reading or recording head in either direction.

The mechanism for feeding the tape through the record reading and recording head is power driven, but in all respects independent of the power by which the tape reels are rotated. By means of the mechanism briefly described, the tape may be reeled or unreeled and fed through a record reading or reproducing head at high speed and without substantial torque or tension on the tape.

This application is a division of the original application for United States patent filed by James A. Weidenhammer and Walter S. Buslik on May 28, 1952, Serial No. 290,396, now abandoned, for Tape Feed Mechanism. In the aforesaid application claim is asserted to that part of the invention herein which concerns itself with the drive and control of the tape reels to provide a pair of tape loops on which the read-write head feeding mechanism herein may draw when called upon to feed tape through the readwrite head in either of two directions. This divisional application is for the purpose of asserting claim to the novel mechanism disclosed herein for feeding the tape through the read-write head in either of two directions and such other inventions that have not been claimed in said aforesaid application.

The details of the mechanism illustrated in the drawings for the purpose of showing an operative embodiment of the invention will become clear as the description proceeds and in which like reference numerals indicate like parts, and wherein:

Fig. 1 is a front elevational view of the tape feeding mechanism with which this invention is concerned;

Fig. 2 is a side elevational view of the tape feeding mechanism with the upper portion of the outer casing broken away to show the location of underlying mechanism;

Fig. 3 is a view on line 3-3 of Figs. 2 and 4 illustrating the tape driving mechanism and certain adjuncts thereto;

Fig. 4 is a plan view of the tape reel drive mechanism comprising electromagnetic clutches and brakes;

Fig. 5 is a view on line 5-5 of Fig. 4 showing parts in cross-section and other parts in full line;

Fig. 6 is a side elevational view of a vacuum column provided for tape loop control;

Fig. 7 is a front elevational view of the vacuum column of Fig. 6;

Fig. 8 is a plan view of a vacuum operated switch used in connection with the vacuum columns of Figs. 6 and 7;

Fig. 9 is a cross-sectional view on line 99 of Fig. 8;

Fig. 10 illustrates the tape drive mechanism and the means for biasing the mechanism into tape driving position, the view showing the parts biased into position for driving the tape in a forward direction;

Fig. 11 is a diagrammatic view of the mechanism shown in Fig. 10 with the parts thereof biased into position to stop tape movement following feed of tape in a forward direction;

Fig. 12 is a diagrammatic view such as that in Fig. 11 and shows the mechanism biased into position to efiect reverse feed of the tape;

Fig. 13 is a diagrammatic view such as those in Figs. 11 and 12 with the parts biased into position to halt tape feed following reverse feed of the tape;

Fig. 14 is a side elevational view of certain type coil sensing mechanism.

Fig. 15 is a front elevational view of mechanism along line 1515 of Fig. 14 showing in particular a pair of tape coil sensing arms and associated contact operating fingers;

Fig. 16 is a view on line 1616 of Fig. 14;

Fig. 17 is a detail view of a lost-motion mounting for the gear element employed in the construction of Figs. 14 through 16; a

Fig. 18 is a view corresponding in general to Fig. 14,

sarcoma wherein parts are shown in cross-section and showing also the connection between the tape coil sensing mechanism and a tape reading head mechanism whereby relative separation between a tape reading head and its cover is effective;

Fig. 19 is a sectional view on line 1919 of Fig. 18 showing the position of the parts with the tape coil sensing arms in one position;

Fig. is a view similar to that of Fig. 19 but shows the respective parts in a different position of adjustment;

Fig. 21 is a view which corresponds in general to Fig. 15 but wherein is shown a modified form of mechanism;

Fig. 22 is a cross-sectional view through Fig. 21 taken on a line disposed axially in respect to the operating shafts.

Fig. 23 is a view taken from the rear of Fig. 21 to illustrate certain operating gears and linkages;

Fig. 24 is an elevational view taken from the back of the device illustrating modified mechanism for causing relative separation between a tape reading head and its cover;

Fig. is a cross-sectional view on line 2525 of Fig. 24;

Fig. 26 is a transverse cross-sectional view on line 2626 of Fig. 24;

Fig. 27 is a diagram of the electrical control circuit for controlling tape feed through the tape reading head;

Fig. 28 is a diagram of the electrical control circuit for biasing the tape feed mechanism into forward or reverse feed position;

Fig. 29 is a diagram of the electrical control circuit by which rotation of the tape reels is controlled; and

Fig. is a diagram of the motor control and power supply circuit.

A general understanding of the machine and its function may be atained by reference to Figs. 1 and 2 of the drawings. A pair of tape reels adapted to hold a coil of record tape are intermittently driven to provide a pair of tape loops upon which the mechanism for feeding the tape through the tape sensing head may call as the tape is to be fed in either of two directions. A tape reel 10 which we shall designate as a file reel is mounted on a drive spindle 12. It may be asumed that the reel 10 has thereon a coil of tape 14 on which data has been recorded and from which the tape is to be fed through a tape read ing and recording head 16. In its forward feed direction, the tape will pass through the tape reading head 16 and will be coiled on a second reel 18 which may be designated herein as a machine reel. The machine reel 18 is mounted on a drive spindle 20.

The file reel drive spindle 12 and the machine reel drive spindle 20 are selectively rotated in either direction by a pair of motors 22 and 23. The motors 22 and 23 normally impart constant drive to a pair of electromagnetic clutch mechanisms mounted on each of the drive spindles 12 and 20. An electromagnetic brake is mounted on each of the drive spindles so that the spindles 12 and 20 may be locked against rotation. The nature of the electromagnetic clutches and the electromagnetic brake will be developed in greater detail at a later point herein.

Upon selective clutching of the electromagnetic clutch mechanisms in drive relation to the drive spindles 12 and 20 these spindles and consequently the tape reels attached thereto may be caused to reel or unreel tape from the coil thereon.

Since the mechanism is designed for high speed feed of tape through the tape head 16, it is important that a supply of tape be provided with little load or tension thereon, and to this end the driving mechanism for the reels 10 and 18 provides a pair of tape loops disposed in a pair of tape control columns 24 and 26. Each of the columns 24 and 26 has therein means responsive to the position of the respective tape loops for maintaining a relatively stable position of these loops within the columns. The loop sensitive means within the columns 24 and 26 control the reel drive mechanism in such manner that the loops, so to speak, are self-compensating. The tape reel drive mechanism for each reel operates independently of the other, and both reels are driven independently of feed of tape through the tape head 16.

Tape from the loop supply in the columns 24 and 26 is driven through the tape head 16 by means of a pair of constantly rotating tape drive capstans. In Fig. 1 a tape drive capstan 28 may be deemed to be constantly 1 rotated in a clockwise direction, and may consequently be designated as the reverse drive capstan. A similar constantly rotating capstan 30 may be deemed to be driven in a counterclockwise direction and may, therefore, be designated as the forward drive capstan. In connection with the drive capstans 28 and 30, there are provided a pair of tape moving idler pulleys 32 and 34. The pulley 32 is adapted to move a tape trained thereabout into driving contact with the reverse drive capstan 28, while the tape moving pulley 34 is adapted to move a tape trained thereabout into driving contact with the forward drive capstan 30. As will be pointed out more fully as the description hereof proceeds, the tape moving idler pulleys 32 and 34 are mounted on a common linkage system which is so designed as to impart the proper related movement to the pulleys for selectively driving a tape either in a forward or a rearward direction through the tape head 16.

A non-rotary stop capstan is also associated with each of the tape moving idler pulleys, so that these pulleys may be moved into contact with their related stop capstans to hold the tape stationary. Thus the idler pulley 32 has associated therewith a stop capstan 36 which we shall designate herein as the forward stop capstan, and the tape moving idler pulley 34 has associated therewith a stop capstan 38 which we shall designate as the reverse stop capstan.

The mechanism for driving the tape reels 10 and 18 may now be referred to in connection with Figs. 3, 4 and 5 of the drawings. The spindles 12 and 20 are mounted for rotation in a frame member 40. The spindle 12 has mounted thereon a file reel brake 42, and electromagnetic reeling clutch 44 and an electromagnetic unreeling clutch 46.

The machine reel spindle 20 has mounted thereon an electromagnetic machine reel brake 48, and electromagnetic unreeling clutch 50 and an electromagnetic reeling clutch 52.

The drive rings of the clutch elements 4452 are adapted for continuous rotation under the infiuence of the drive motors 22 and 23.

By reference to Fig. 3 of the drawings it will be seen that the drive motors 22 and 23 are mounted on supporting structures 54 and 56 respectively, in such position that the motor shafts 58 and 60 respectively extend forwardly into substantially vertical alignment with their related magnetic clutch structures.

By reference to Fig. 4 of the drawings it will be seen that the first pair of clutches 44 and 50 are in substantial, transverse alignment on their respective shafts and that the second pair of clutches 46 and 52 are also in substantial, transverse alignment on their respective shafts. The clutches 44 and 50 are driven in a counterclockwise direction by the motor 22 through a drive belt 22a while the clutches 46 and 52 are driven in a clockwise direction by the motor 23 through a drive belt 23a, the motor shaft 58 having a normal clockwise rotation and the motor shaft 60 having a normal counterclockwise rotation.

Noting Fig. l of the drawings, it may be seen that the file reel 10 is disposed for reeling tape thereon when driven in a counterclockwise direction, while the machine reel 18 is disposed for tape winding upon clockwise rotation. In light of this arrangement, the clutch 44 operates as a reeling clutch for the file reel 10 while the clutch 50 operates as an unreeling clutch for the machine reel 18. By the same token the clutch 46 operates as an unreeling clutch for the file reel 10, while the clutch 5 52 operates as a reeling clutch for the machine reel 18.

The file reel brake 42 and the machine reel brake 48 each has the outer shell thereof fixed to the frame member 40 by means of machine screws 62, thereby providing an anchor for these shells when either brake is energized to lock its respective shaft against rotation.

Fig. 5 of the drawings illustrates the specific nature of the brake and clutch units. These units are of identical structure, and a description of the clutch 50 will therefore suifice as a description of all. The driving member 64, including the ring or shell 50, is mounted on the shaft 20 for free rotation thereon. The driving member includes an end plate 66 in which is mounted a pair of commutator rings 68 which provide a current path for an electromagnetic coil 50a mounted within an annular recess in the driven member 64 and held therein by an annular plate 72. The opposite face of the structure has fixed thereto a closure plate 74. Suitable hub rings 76 support the driving member for rotation on the shaft 20.

A driven member 78 is spaced from and disposed between the annular plate 72 and the closure plate 74. The driven member 73 is keyed to the shaft 20 by means of a suitable keying structure 80.

It will be apparent now that when the driving member 64 and the driven member 78 are caused to rotate in unison, drive will be imparted to the shaft 20. Such drive coupling is achieved through the use of iron powder disposed between the driving member 64 and the driven member 78. The circumference of the annular plate 72 is such that its periphery is spaced from the inner wall of the recess formed in the driving member 64. This in effect forms an annular channel adapted to receive an inturned flange 34 of the driven member 78. The inturned flange 84 is so positioned as to provide a substantially equal space on opposite faces thereof in reference to the oppositely disposed walls of the annular channel. Iron powder in a sufficient amount to substantially fill the remaining space of the channel will serve to freeze the iron powder and thereby clutch the inturned flange 84 of the driven member 78 to the driving member 64 of the clutch structure whenever the coil 50a is energized.

Centrifugal force acting on the iron powder ordinarily maintains the powder in the channel adjacent the inturned end 34 of the driven member 78. However, in order to avoid possibility of the loss of the powder into the bearing structure ofv that assembly, the annular plate 72 is provided with an annular rib 86-88 which extends into an annular groove 8884 on the inner face of the driven member 78. The annular rib 8688 is outwardly slanted to provide a trough for powder that may find its way inwardly along the clutch structure. A similar rib and trough is formed on the outer face of the driven member 78 for preventing passage of powder inwardly along the outer face of the driven member. Any residual particles of powder will be caught in a groove 92 that is formed in the inner face of the driven member near the axial portion thereof.

The commutator rings 68 are in contact with a brush 94 carried on the end of a resilient contact strip 96 which is connected into the control circuit by means of terminal screws 98 (Fig. 4).

The clutches at the rear end of the spindles 12 and 20 are of the same construction as that described hereinabove, and their mounting on their respective shafts is the same except that they are reversed so that the end plate 66 is oppositely disposed to present the commutator rings in a more accessible position. The brake assemblies 42 and 48 are also constructed exactly like the clutch assembly just described, .and the manner of mounting these on their respective shafts is also the same with the exception that the end plate 66, and consequently the shell or what would correspond in the clutch assembly to the driven member, is held stationary. It now follows that the energization of the coils in the several clutch assemblies will result in the corresponding for- Ward or reverse drive of the respective spindles 12 and 20. By the same token these spindles will be held against rotation whenever the coil in the brake assembly associated therewith is energized. Since the shells of the brakes 42 and 48 are fixed, the leads for energizing the electromagnetic coils therein may be taken through the end wall of the brake assemblies. As will be seen at a later point herein, the control circuit is such that drive through either of the clutches on a drive spindle will take place only upon deenergization of the associated brake assembly coil, and that ordinarily the coil in the brake assembly will be energized to hold its associated spindle against rotation when the clutch coils are deenergized.

It has been mentioned heretofore that the position of the tape loops in control columns 24 and 26 is utilized to control the rotary movement of the tape reels. Herein, by way of example, there has been illustrated a vacuum switch control system for achieving this objective. The control columns 24 and 26 are of the same construction, and the specific nature thereof may best be seen in Figs. 6 and 7 of the drawings. In these figures of the drawings is illustrated the control column 26 shown at the right in Fig. 1. However, since the column 24 is of the same construction, a description of Figs. 6 and 7 will serve as a description of both'control columns. The column herein illustrated comprises a pair of side walls 100, a back panel 102, a transparent face panel 104 and a bottom wall 106, all joined together in air-tight contact.

At the base of the columns 24 and 26 is a header 108 with which the columns communicate. The header 108 is connected with a vacuum pump 110 adapted to be driven by a suitable motor VPM. The foregoing provides a structure by means of which the control columns 24 and 26 may be evacuated when the upper ends thereof are closed against the atmosphere.

At the upper end of each control column is a guide plate 112, whose arcuate lower face is slightly spaced from a corresponding arcuate upper edge of the transparent face panel 104. The lateral extremities of the guide plate 112 serve to support the opposite bights of a tape loop within the control column and the arcuate slot formed between the lower arcuate face of the guide block and the upper edge of the face panel constitutes a guide through which a tape loop may be threaded for insertion into the control column. The face plate 104 has formed at the bottom thereof a hand opening 114 normally closed by an air-tight closure 116 held in position by a spring clip 118. This opening constitutes a clean-out passage.

The side walls of the vacuum columns 24 and 26 are of a width substantially equal to the width of the tape 14. When a tape loop is formed, therefore, in either of the vacuum columns 24 or 26, the oppositely disposed marginal edges of the loop will be in substantial contact with the base plate 102 and the face plate 104 of the respective vacuum columns. The back of the tape in the tape loop is spaced from the side walls of the vacuum columns through substantially the entire length of the loop but the bight of the loop is in substantial contact with the side walls. This disposition of the tape loop within the vacuum columns 24 and 26 is assured by the tape guide structure. As the tape comes from the file reel 10, it passes over a guide idler 10a. As the tape is fed to and from the machine reel 18, it too passes over a guide idler 18a. The horizontal distance between the outer periphery of the guide idler 10a and the drive capstan 28 is somewhat less than the spacing of the inner faces of the column side walls 100. The same is true of the horizontal spacing of the guide idler 18a and the drive capstan 30 at the right of the structure.

The particular horizontal spacing of the guide idlers and their associated drive capstans assuresthat the inner face of the tape is in contact with the oppositely disposed ends of theguide plate 112at the topof the vacuum columns 24 and 26. These guide plates, therefore, determine the spacing of the tape bights at the entrance to the columns. Since the distance between the ends of the guide plate 112 is somewhat less than the internal width of the vacuum columns, the back of the tape will be spaced slightly from the column side walls through the major portion of the tape loops, the loops, however, widening out at their lower ends to contact the side walls of the columns, thereby forming an air seal between the lower portion of the tape loop and the column walls.

Spaced along the length of each of the control columns 24 and 26 are two vacuum operated switches, the details of which are shown in Figs. 8 and 9. In Fig. l of the drawings the vacuum switch LUV is the left upper vacuum switch, while the switch LLV is the left lower vacuum switch. In similar fashion the control column 26 has a right upper vacuum switch RUV and a right lower vacuum switch RLV.

The vacuum switches have a normally closed contact point and a normally open contact point. The switches communicate with the interior of their respective control columns through an aperture in the back plate 162 thereof. By reference to Fig. 9 it will be seen that the switch structure is encased in a shell 120 which fits tightly against a base plate 122, the base plate being attached to the back panel 102 of the control column so that an aperture 124 of the back panel registers with a passage 126 in the base 122 of the switch structure. Within a cavity formed between the base plate 122 of the switch structure and an overlying block 128 is a pressure responsive diaphragm 130 to which a contact operating shaft 132 is attached, this connection between the diaphragm and the shaft 132 being air-tight. Adjustably secured to the opposite end of the contact operating shaft 132 is a spring contact finger 134 having contact points thereon adapted to contact corresponding points on fixed contact fingers 136 and 140. Outward deflection of the diaphragm 130 under the influence of atmospheric pressure when its associated control column is evacuated will cause the points on the contact fingers 134 and 140 to transfer.

For the sake of uniformity herein it may be assumed that the contact carried on the finger 136 is a normally closed contact while the contact on the finger 140 is a normally open contact. Furthermore, the contact on the arm 136 in Fig. 9 may be designated as the RUV-1 contact, whereas the contact on the arm 140 may be designated as the RUV-2 contact. bering will be applied to the other vacuum switches when the circuit description is rendered in connection with Fig. 29 of the drawing.

Under the foregoing conditions, any time that the diaphragm 130 is subjected to vacuum within the vacuum columns, atmospheric pressure on the opposite side of the diaphragm will cause transfer of the switch points, i. e. the points RUV-1 of Fig. 9, for example, will open, while the points RUV-2 will close.

Electrical connections with the switch blades are made through a connecting bushing 138 at one end of the base plate 122.

During normal operation of the machine, the tape loops in columns 24 and 26 will be disposed between switches RUV-RLV and LUV-LLV of the respective column pairs. Under these conditions the switches LUV and RUV are subject to atmospheric pressure only, whereas switches LLV and RLV are influenced by vacuum in the columns 24 and 26, the tape loops constituting a column air seal above the switches LLV and RLV.

The device is designed so that the tape loops in the control columns 24 and 26 are maintained between the respective upper and lower vacuum switches. To this end the vacuum switch LUV is in the control circuit of A similar system of numthe magnetic coil in the unreeling clutch 46, while the vacuum switch LLV is in the control circuit for the magnetic coil of the reeling clutch 44. In like manner the vacuum switch RUV is in the control circuit of the unreeling clutch 50, while the vacuum switch RLV is in the control circuit for the reeling clutch'52.

Should either tape loop drop below its lower vacuum switch, such switch will be subject to atmospheric pressure on both sides of its diaphragm 130, causing the contact points thereof to transfer. Consequently, under such conditions the switch LLV will call into action the file reel reeling clutch 44 and the switch RLV will call into operation the machine reel reeling clutch 52.

Such tape loops will be taken up by the reeling action of the respective reels, or either thereof, until the bight of the loop is above the lower control column switch, whereupon the switch will again transfer its contact points under influence of vacuum within the column.

In like fashion the upper vacuum switches LUV and RUV which are subjected to atmospheric pressure on both sides during normal operation of the machine will transfer their contact points when the bight of the tape loop rises above these switches. Under these conditions the upper switch will be subject to the vacuum within their respective control columns. The low pressure on the inner side of the diaphragm will thereupon permit atmospheric pressure on the opposite side to transfer the contact points of the upper switch structure. Upon such transfer the switch LUV will serve to energize the coil in the unreeling clutch 46, and the switch RUV will call into action the unreeling clutch 59 whereby the file reel 10 and machine reel 18 respectively, or either one of them, will be rotated to the unreel tape therefrom and thereby lengthen the loop in the control columns 24 and 26 respectively until the bight thereof once more drops below the upper switches LUV and RUV.

From the foregoing it will be seen that the operation of the tape reels 10 and 18 is in effect a self-compensating operation whereby the tape loops in the control columns 24 and 26 are maintained in an optimum position. Furthermore, it is apparent that the controls for the reels 10 and 18 are independent one from the other.

The second contact point of each vacuum switch is used to provide a circuit for their respective brake coils. When the control circuit is described, it will appear that a circuit is established through closed points of switches LUV and LLV to energize the coil of the file reel brake 42 and that a circuit is provided through closed points of switches RUV and RLV to energize the coil in the machine reel brake 48. It is intended that the brake coils be energized whenever the reeling and unreeling clutches are deenergized.

The mechanism for driving the tape through the tape head 16 in a forward direction is shown in Fig. 10 of the drawings, Figs. 11 through 13 diagrammatically illustrating the other drive and stop positions. The drive capstans 28 and 30 are constantly driven by means of a motor 142 (Fig. 3) whose shaft 144 rotates in a clockwise direction. The drive capstans 23 and 30 are journalled for rotation in the face panel 13 of the machine, and the shafts 28a and 30a extend to the rear of the panel 13 where they have atfixed thereto belt pulleys 146 and 148 respectively. A drive belt 150 is trained about the pulleys 146, 148 and about a motor shaft pulley 152 so that upon clockwise rotation of the motor shaft 144 the capstan shaft 28a will be rotated in a clockwise direction while the capstan shaft 30a will be rotated in a counterclockwise direction. This is accomplished by the use of an idler pulley 154 mounted on a spring-biased lever 156.

By reference to Fig. 10 of the drawings it will be seen that the tape moving idler pulleys 32 and 34 are mounted for rotation at the free end of levers 158 and 160 respectively. The inner ends of the levers 158 and 160 are fixed to pivot shafts 162 and 164 respectively. The pivot shafts 16 2 and 164 are journalled for rocking movement in the face panel 13, and each of these shafts has vattached thereto a short, upwardly extending link 166 and 168 respectively. The inner, free ends of the links 166 and 168 have pivoted thereto levers 170 and 172 respectively which have their opposite ends pivoted to a common operating lever 174.

With the foregoing structure the tape moving idler pulleys 32 and. 34 may be selectively engaged with their related drive capstan and with their stop capstan. Thus the tape moving idler pulley 32 may be brought into contact with the reverse drive capstan 28 or with the forward stop capstan 36. The tape moving idler pulley 34 may be selectively engaged with the forward drive capstan 30 or with the reverse stop capstan 38. The stop capstans 36 and 38 are eccentrically mounted in the face panel 13 by means of screws 36a and 38a about which the capstans may be adjusted to vary their braking effect.

In order to impart controlled movement to the tape moving idler pulleys 32 and 34, there has been provided herein a forward-reverse actuator 176 comprising a pair of aligned, high speed relay magnets 176a and 176b and a stop or drive actuator 178 which consists of a coil 180 in a field of high flux density caused by a permanent magnet 182. The high speed relay coils 176a and 17612 are mounted on a supporting yoke in axial relation to each other and with the provision of a space between the magnets to accommodate a pivoted armature 184 to the free end of which the operating lever 174 is attached by means of a pivot stud 186.

The coil 188 of the stop-drive actuator has aflixed thereto a rod 188 which is connected to the operating lever 174 midway between the connections of the levers 170 and 172.

When the relay magnet 176b is energized, the armature 184 will be attracted thereto and the operating lever 174 will be biased to the right in Fig. 10. This elevates the tape moving idler 32 a half gap width above the tape moving idler 34. When the stop-drive actuator 178 is energized to repel the coil 180 thereof, an upward thrust will be delivered to the rod 188. This will further move the drive linkage to force the tape moving idler pulleys downwardly and outwardly until the tape moving idler pulley 34 is engaged with the forward drive capstan 30. This will cause the tape 14 to be driven downwardly into the control column 26.

The foregoing describes one of four stable positions into which the tape moving idler pulleys may be biased. The three other positions are illustrated in Figs. 11, 12 and 13 of the drawings.

Fig. 11 shows the position of the tape moving idler pulleys for stopping tape feed following forward feed of the tape. At this point it may be appropriate to mention that the tape is always pulled through the tape head 16 and is stopped by braking the tape at a position behind the tape head 16. This will insure sufficient tape tension at the tape head 16 at all times.

Reverting to Fig. 11 of the drawings it will be seen that the tape 14 is stopped by engaging the tape between the forward stop capstan 36 and the tape moving idler pulley 32. To achieve this function, the magnet 1761; must remain energized, but the flow of current through the stop-drive actuator 178 is reversed whereby the coil 180 is attracted to the permanent magnet 182. This results in a downward pull on the rod 188. Such pull on the linkage system will tend to raise both tape moving idler pulleys 32 and 34, but-since the tape moving idler pulleys 32 in the forward driveposition was higher than the pulley 34, the idler pulley 32' engages the forward stop capstan 36 to brake tape movement. Engagement between the taipe moving idler pulley 32 and its forward stop capstan 36 results from the upward bias given to the tape moving idler pulley 32 under the influence of the magnet 1.761).

In Fig. 12 of the drawings, the tape 14 is moving in a reverse direction. To bias the tape moving idler-pulley 10 32 into contact with the reverse drive capstan 28,.it' is necessary to energize the magnet 176a. This attracts the armature 184 and pulls the operating lever 176 to the left in Fig. 12. This will serve to drop the tape moving idler pulley 32 one-half gap below the idler pulley 34 and condition the tape moving idler pulley 32 for engagement with the reverse drive capstan 28 when the moving coil is energized to cause an upward movement of the rod 188. Such movement will serve to project the tape moving idler pulley 32 into engagement with the reverse drive capstan 28, whereby the tape 14 is driven in a reverse direction, i. e. from right to left in Fig. 3 of the drawings.

The reverse stop position of the tape drive mechanism is shown in Fig. 13 of the drawings, wherein the tape moving idler pulley 34 is brought into engagement with the reverse stop capstan 38. To achieve this engagement, the magnet 176:! must remain energized but the current in the moving coil 188 is reversed, whereby the coil is pulled downwardly so that the rod 188 exerts a downward pull on the operating lever 174 with a consequent upward bias of the tape moving idler pulley 34 into contact with the reverse stop capstan 38.

In Fig. 1 is shown a pair of tape contact arms 190 and 192. These arms are mounted for pivoting movement so that the ends thereof may ride freely in contact with the tape coils on the respective reels 10 and 18. Through this medium is provided a control mechanism to prevent the complete run-out of tape from the reels. Figs. 14 through 20 illustrate the particular details of one form of tape arm mechanism, while Figs. 21 through 23 show a modified form. Specific reference may first be made to that form of the mechanism shown in Figs. 14 through 20.

The tape arms 198 and 192 have tape contacting rollers 194 and 196 at the free ends thereof. These rollers are freely rotatable in the bifurcated free end of the arms 198 and 192 respectively, so that they ride lightly on the tape coil of the tape reels 10 and 18. The inner ends of the arms 190 and 192 are keyed to shafts 198 and 208 respectively. These shafts are journalled for rocking movement in a mounting block 202 which has a flange 204 by means of which the mounting block is mounted in the face panel 13 of the machine as shown in Figs. 1 and 18. An operating shaft 286 is mounted for rocking movement in the block 282 at a point midway between the shafts 193 and 200 and slightly thereabove. The forwardly projecting end of the operating shaft 286 has an operating handle 208 aifixed thereto.

The distal ends of the shafts 198, 200 and 266 extend beyond the rear face of the mounting block 202 at which point intermeshing gears are mounted on the respective shafts. The shafts 198 and 200 have mounted thereon a pair of gears for limited rotation in respect to the shaft. Fig. 17 of the drawings illustrates one of these gears which may be recognized as the gear 210 on the shaft 208. The other shaft 198 has a gear 212 mounted thereon in similar fashion to permit limited relative movement between the shaft and the gear.

The relative movement between the shafts 198 and 20% and their respective gears 212 and 218 is for the purpose of permitting movement of the respective arms 190 and 192 and a pair of contact making and breaking fingers 228 and 222 which are fixed to the ends of shafts 198 and 288 respectively, without reference to rotation of the operating handle 288.

With reference to Figs. 17, 19 and 20 of the drawings, it will be seen that the gears 210 and 212 are formed with a pair of outwardly diverging slots, and that a pair of pins 214 and 216 carried by the shafts 208 and 198, respectively, extend into the slots of their associated gears. Thus while the gears 210 and 212 are adapted for limited movement in respect to their respective shafts 2110 and 198, the slot walls will engage the pins 214 and 216 and rotate the shafts 198 and 200 when engagement between the pins and the slot walls is effected, as during rotation of the handle 208.

seesaw The manner in which movement of the handle 208 is imparted to the gears 210 and 212 is as follows: The operating shaft 206 has a gear 218 keyed thereto, and this gear, as best seen in Fig. 16 of the drawings, is in driving contact with the gear 212, this latter gear being relatively wide. The gear 210 in turn is in mesh with and drives the gear 212. By means of this arrangement, rotation of the shaft 286 is imparted through the gear 218 -'to the gear 212 and to the gear 210 with the consequence that the shafts 198 and 200 are rotated when the respective pins 216 and 214 come into engagement with the slot walls in their associated gears.

As intimated hereinabove, the shafts 198 and 200 have attached thereto a pair of circuit making and breaking fingers 220 and 222, respectively. The free ends of these fingers mount adjustable studs 224 and 226, respectively. Contact between the studs 224 and 226 and a pair of normally open file and machine reel contacts FRS and MRS, respectively, shown at the top of Fig. 3 of the drawings will influence the control circuit as will be more fully described at a later point herein.

From the foregoing it will be seen that rotation of the handle 208 will transmit a torque through the gears to the tape contact arms 190 and 192 and to the circuit making and breaking fingers 220 and 222 to elevate the arms and the fingers. While the lost-motion connection between the gears 210 and 212 and their respective shafts 2G8 'and'198 permits raising of the tape contact arms 198 and 192 and the circuit making and breaking fingers 22 8 and 222, the contact arms 198 and 192, and consequently the circuit making and breaking fingers 228 and 222, are free to follow the tape coil on the reels 10 and 18.

The inner end of the operating shaft 206 has a plate 228 attached thereto, and this plate carries a pair of rearwardly extending studs 230 and 232. The stud 230 supports one end of a coil spring 234 which has its other end attached to a fixed pin 236. The stud 230 is so located on the plate 228 that the torque of the spring 234 is along a line which includes the shaft 286 when the operating handle 208 is in a vertical or open position. Through this medium the mechanism just described has a stable, open position under the influence of the spring 23-4. The second stud 232 mounts an operating link 238 by means of which a tape head cover is opened and closed.

The tape head 16 (see particularly Fig. 18 of the drawings) has a cover 248 pivoted on a block 242 which is attached to the rear face of the machine panel 13. Immediately to the rear of the tape head 16 and slightly thereabove is an aperture 244 through the face panel of the machine, providing passage for a rearwardly projecting extension 246 of the reading head cover 240. By reference to Fig. 18 of the drawings it will be seen that the cover 240 is pivoted on the block 242 by means of a pivot pin 248 about which the cover may rock into open and closed position in respect to the head 16. A spring 258 is coiled about the pivot pin 248 and has oppositely disposed portions, one of which engages the rear face of the machine face panel and the other of which engages the lower face of the rearwardly projecting cover extension 246. By this arrangement the cover 240 is normally biased into closed position.

Rocking movement of the shaft 206 in the bearing blocking 202 is limited by means of a stop plate 252 which is adapted to engage a stop pin 252a at the rear of the face of the block 202. The stud 230 is also adapted to open and close 'aithr'ead handle switch THC as will be developed more fully hereinafter.

From the foregoing it will be apparent that whenever the operating handle 208 isrotated to a vertical position such as that shown in Figs. and 18 of the drawings, the tape contacting arms 190 and 192, and consequently the tape contacting rollers 194 and 196, will be raised so that tape reels may be removed from or placed upon I 272 respectively.

the spindles 12 and 20. At the same time, the circuit making and breaking fingers 220 and 222 will be elevated. Concurrent with these movements is the opening of the tape head cover 240 through stud 232, operating link 238 and the rearwardly projecting cover extension 246. With the mechanism in open or elevated position, the spring 234 will hold the parts in such position to permit the changing of reels and threading of tape as may be required.

When the operating handle 288 is returned to its horizontal position the tape sensing arms and 192 will return to their normal position in contact with the tape coil 011 the associated tape reels 10 and 18. It may be noted, however, that the lost-motion connection between the shafts 193 and 200 will permit independent movement of the tape sensing arms 198 and 192 and their associated circuit making and breaking fingers as may be required by the size of the tape coil on either of the reels 10 or 18.

The modified tape contact arm mechanisms shown in Figs. 21 through 23 of the drawings has effective operations which are substantially the same as those of the form shown in Figs. 14 through 19 of the drawings but performs these operations in a somewhat different fashion. In this form of the invention a pair of tape contact arms 254 and 256 are secured to the front end of a pair of shafts 258 and 260, respectively. The shafts 258 and 260 are mounted for rocking movement in a mounting block 262 which has a flange 264 by which the block may be mounted in the face panel 13 of the machine.v Attached to the rear end of the shafts 258 and 260 are a pair of circuit making and breaking fingers 266 and 268, respectively. Mounted for free rotation on the shafts 258 and 260 are a pair of gears 270 and These gears have elongated hubs 274 like that shown in reference to the gear 272 in Fig. 22 of the drawings. Affixed to the elongated hub portion of the gears for rotation therewith are a pair of fingers 276 and 278. Each of the circuit making and breaking fingers 266 and 268 has an outwardly turned flange portion 280 and 282, respectively, which overlies the outer extremities of the fingers 276 and 278, respectively. As a consequence of this relationship, whenever the fingers 276 and 278 are elevated, their extremities may engage their related flanges 280 and 282 respectively and thereby elevate the circuit making and breaking fingers 266 and 268. This motion results in the rocking of shafts 258 and 268 with the result that the tape contact arms 254- and 256 are also elevated. The circuit making and breaking fingers 2'66 and 268 have at their extremities adjustable studs 284 and .286, respectively, which are adapted to contact and close the reel switches FRS and MRS, respectively, shown in Fig. 3 of the drawings when either or both of these circuit making and breaking fingers are in their lower position. Thereby, the reel switches will be closed whenever the coil of tape on either reel becomes dangerously depleted.

In order to manuallyraise and lower the tape sensing arms 254 and 256 and their related circuit making and breaking fingers 266 and 268, an operating shaft 288 is journalled for rocking motion in the block 262. An operating handle 290 is fixed to the forward end of the shaft 288. The rear end of the shaft 288 has attached thereto a cam'plate 292 to which is pivoted one end of a link 294. The other end of the link 294 is pivoted to thefinger 278.50 that rocking movement of the shaft 288 will be imparted to the finger 278 and thereby to the gear 272. The gears 270 and 2'72 being in mesh with each other will transmit operating torque from the gear 272 to-the gear 270 and thereby to the other finger 276.

It will be seen from the foregoing description with particular reference .to ,Fig. 23 of the drawings, that a mechanism has been provided wherein manual rotation of the handle 290 will cause rotation of the gears 270 and 272 with the consequent rocking movement of the fingers 276 and 278. When the handle 290 is rocked to a vertical position, and if the tape sensing arms 254, 256 and the circuit making and breaking fingers 266 and 268, or either of them, are in a lower position, such movement of the handle will be effective to rotate the shafts 258 and 260 and thereby elevate the tape sensing arms 254-256 and the circuit making and breaking fingers 266 and 268.

In lieu of the springs 234 used in the previously described form of the mechanism for imparting stability to the assembly in its open position, there has been provided in the modified form a spring-pressed detent 296 which is adapted to engage a recess 298 in a hub 301) fixed to the shaft 283.

In this modified form of the mechanism the cam plate 292 operates both as an eifective stop and as an operator for the thread handle switch THC. The thread handle switch THC (Fig. 21) is so positioned thatthe edge of the cam plate 292 that is adjacent its junction with the link 294 comes into contact with the thread handle switch to close the same. The cam plate 292 has a shoulder portion 362 which limits the rocking movement of the shaft 288 in one direction by engagement with a stop pin 304 which projects from the rear face of the mounting block 262. Rocking movement of the shaft 288 in the opposite direction is limited by engagement between the upper edge of the cam plate 292 and the hub portion of the finger 278.

It will be observed that the modified form of the tape sensing mechanism embodies no mechanical connection for the tape head cover. This is due to the fact that it is contemplated to use the modified form of the tape sensing assembly with a tape head which is bodily slidable in a vertical path in the face plate of the machine, and which is under the control of a solenoid which may be impulsed in any suitable fashion whenever it is desirable to drop the tape reading head from its normal tape reading position.

Figs. 24, 25 and 26 of the drawings illustrate the structure of a modified form of tape head 16a. Herein the tape head has a cover 248a supported on a plate 366 which projects forwardly from the face panel 13 of the machine. It is contemplated in this structure that the tape head 16a be dropped away from its cover 240a rather than separation of the cover from the reading head as in that form shown in Fig. 18 of the drawings.

To secure this function, the tape head 16a is secured to a base plate 308 which is mounted for sliding movement on the face panel 13 of the machine between a pair of guides 310 and 312, the base plate 308 being mounted in the guides 310 and 312 by means of anti-friction bearings 314.

The base plate 308 and consequently the tap head 16a is held in its upper or operative position by means of a pair of coil springs 316. It may be noted that extending rearwardly from the base plate 308 and through 'a pair of slots 318 in the face panel of the machine are a pair of studs 320 to which one end of the coil springs 316 are attached, the other ends of the :coil springs 316 being fixed to studs 322 projecting rearwardly from the face panel of the machine. It will be seen, therefore, that while the base plate 3413 is adapted for movement in a vertical path within the guides 310 and 312, the same is normally held in its upper position where it is in juxtaposition to the cover 240a under the influence of the coil springs 316.

Whenever it becomes necessary to drop the tape head 16a away from its cover 240a, as may be the case when tapes are changed, there has been provided in this form of the mechanism an operating solenoid 324 comprising a coil 326 and a core 328. The outer end of the core 328 has pivoted thereto a link 330 which at its other end is pivoted to a rocking lever 332. The rocking lever is mounted midway between its ends on a pivot stud 334 so that whenever the coil 326 of the solenoid is energized and its core is pulled intov the coil, the upper end of the rocking lever 332 willswing in an are. This motion is utilized to pull down the base plate 368 against the tension of the springs 316 by a connection between the upper end of the rocking lever 33?. and a link 336 which is pivoted to a stub shaft 338 fixed to the base plate 308 and extending rearwardly therefrom through a slot 340 in the face panel of the machine.

It follows from what has been said in connection with the structure shown in Figs. 24 through 26 that whenever the coil 326 of the solenoid is energized its core 328 will be attracted and the linkage system comprising link 330, rocking lever 332, and link 336 will operate to pull the base plate 308 and its associated tape head 16a down wardly and the same will be held in such position so long as the solenoid 324 remains energized. Upon deenergization of the solenoid 324, the coil springs 316 with the aid of a spring 317 will return the base plate 368 and its associated tape head 16a to its upper or operative position.

The mechanism is put into operation by closure of the line switch LS (Fig. 30) which supplies volt alter-nating current to the vacuum pump motor VPM. The same circuit includes transformers T (only diagrammatically indicated) from which are derived the 40 volt power supply and the high voltage power supply. Most of the relays such as those shown in Fig. 29, are connected across the 40 volt power supply line, while the high voltage supply provides the various plate voltages, bias voltages, etc. required by the several electronic units.

As soon as voltage appears on the +40 volt line, the run relay R1 (Fig. 29) is energized through the thread handle contact THC and the safety vacuum switch contact SVS. If there is a tape loop in the control columns 24 and 26, thus forming an air seal between the upper and lower vacuum switches, and if the vacuum motor VPM is operating, the safety vacuum switch SVS in the header 108 (Fig. 1) will be closed by the vacuum built up in the header 108 by the vacuum pump. If the tape sensing arm operating handles 298 or 290 .are in a horizontal position, the thread handle contact THC will be closed.

When the relay R1 is energized, its associated point R1-1 :closes, thereby energizing a heavy duty relay HD. Energization of the heavy duty relay HD causes its HD-l point (Fig. 30) to close and its HD-2 and HD-3 points (Fig. 29) to transfer.

By reference to Fig. 30 of the drawings, it will be seen that closure of the HD-l point .closes the circuit of the capstan motor 142 as well as the circuit of the two reel motors 22 and 23.

If it is desired to feed tape from the file reel 1b to the machine reel 18, a forward key FK (Fig. 28) is pressed to open its contact, or if reverse feed from the machine reel 18 to the file reel 10 is required, a backward key BK is depressed to open its contact. Depression of the forward key PK, for example, removes the 250 volt bias supply from the right side of a binary trigger. As a result, theright side of the trigger is rendered conductive, while the left side is rendered non-conductive. With the left side of the trigger being non-conductive, its plate voltage is high. Thus the voltage on the tube side of a cathode resistor of an associated cathode follower C51 is high .and the grid of a connected power tube PTS is high. With the grid of the power tube PTS being high, the power tube PTS conducts heavily and the forward control magnet 17611 is energized. This will condition the tape moving idler pulley 34 for driving engagement with the forward drive capstan 30.

Thereafter actual tape feeding in a forward direction is started by depressing a tape feed control switch TFS (Fig. 27). Transferring of this switch applies 30 volts to the grids of a power tube PT1 and a power inverter P11, while +10 volts are applied to a power tube PT2 and a power inverter PI2. Power tube PT2 and power inverter P12 are thus rendered conductive, while the 

